Okay so I was interested to learn whether anyone else has experienced fin rot like this. I did my best to get a photo but his water is really murky due to the Neomycin (antibiotic) that I am treating him with, unfortunately it does not seem to be helping after 8 days of treatment. Instead of the edges of his fins receding or large chunks of fin breaking away he gets tiny little pin holes all over his fins and they just seem to sort of decintergrate (sorry spelling). You can see the holes if you look carefully at the photo. This boy was a rescue and was very very unwell when I got him, he has suffered fin rot on many occasions despite keeping his water emaculately clean. He has never seemed 100% well and I think his immune system may be permanently weakened.

My fish has the same thing at the moment and I have no idea what is going on :/
Mine is getting a bit better but a previous fish i had died within a week of having it.
Maybe if you could put up some more info on your tank (heating, size etc) i could help you more.

If the Neomycin isn't effective, you may need to try a different gram negative antibiotic. (Fin rot is usually caused by either water quality issues or gram negative bacterial infections.... And I've seen enough posts from you to know that you're changing the water regularly, which leaves bacterial....)

You could also add something like Vitachem. It contains vitamins and minerals, and gets added directly to the water. It might help strengthen his immune system.

crystalicethorn- He is usually kept in a large barrack tank with 9 other males. Each compartment is heated and filtered and they are cleaned out 2-3 times weekly. I keep no gravel in my betta tanks specifically so that I can keep them nice and clean due to their tendency towards bacterial infections. This guy has been suffering from this for about a month.

LittleBlueFishlets- Originally the treatment plan for the Neomycin was 100% daily water changes and Neomycin dosage for five days, when it wasn't working the vet suggested following the same regime for a further five days. Today is the last day and this guy is still getting worse. I am considering giving him a weeks break from meds with some IAL in his water and then seeing if the vet can suggest another antibiotic that targets gram- negative bacteria. The poor boy has been through so much. I originally bought him as a rescue because he had bad fin rot and velvet. I cleared up the fin rot and velvet but he keeps getting the fin rot back despite his regularly cleaned tank. I try to feed them a good diet too, they get Atisons betta pro pellets twice a day and once a week they get a mixture of frozen black mosquito larvae and brine shrimp. I am planning on getting a large variety of frozen foods for them.....makes life a but more interesting for them and also a varied diet is healthy for them. I will definately look into the vitachem....sounds like he might benefit from it, just hope we can get it here in Australia....even when they don't contain S4 drugs a lot of products are difficult to get here.

logisticsguy- I think I can get the paragaurd from a LFS here so I will definately look into getting some.